Method of fractionally distilling and desulphurizing crude oil



Marh 3, 1936. c. L. SMITH ET Al. 2,032,896

METHOD OF FRACTIONALLY DISTILLING AND DESULPHURIZING CRUDE OIL Filed nec. s1, 1932 Luh. mkmmupk e -uHHlI Patented Mar. 3, 193.;`

METHOD OF FRACTIONALLY DIS'IILIING AND DESULPHURIZING CRUDE OIL Clyde L. Smith, lChicago, Ill., andV Weldon G. Annable, Linwood,.Pa., .assignors to The Pure v Oil Company, Chicago,

Ohio

1li., a corporation of Application December 31, 1932, serial Nattavzz 9 claims. (c1. iss-2s) This invention relates to the treatment of crude hydrocarbon oils, especially mineral oils having a naturally high sulphur content, such as those characteristic of the Michigan and other comparable fields, whereby to provide an economical,

eiective and continuous system for simultaneously fractionally distilling and desulphurizing oils of the type indicated.

An object o'f the invention resides in the provision of a system for distilling hydrocarbon oils of the sulphur-bearing type wherein the oils charged to the system are rst heated suiiiciently lto effect vaporizing of the vaporizable constituents thereof without substantially cracking the oils, and wherein provision is made for bringing the vapors of such distillation into intimate and sustained contact with a circulating body of a treating agent, usually in the form of copper oxide, to the end of enabling the treating agent to react with the vaporized oils to procure a chemical combination of the sulphur compounds present in the vapors with the treating agent, and the resulting extraction of such sulphur compounds from the vapors, the desulphurlzedvapors being subsequently fractionally condensed into oils of different boiling range.

We are aware of the fact that it has been proposed heretofore to desulphurize mineral oils with the use of copper oxide but it is `one of the important objects of the present invention to accomplish this result in a more effective, expeditious and continuous manner in apparatus suitable for use in commercial refineries wherein a relatively large throughput of the oil to be treated and fractionally distilled is necessary, and to accomplish the operation with a higher degree of uniformity than has existed heretofore inv analogous operations and with the employment or utilization of minimum quantities of copper oxide per barrel of oil treated.

In carrying out the invention, the system embodies a still containing one or more tube banks through which the oil to be treated is passed and subjected to distilling temperatures and in the furnace gas outlet of the still there is arranged another bank of tubes through which is passed for heating purposes the copper oxide, or other equivalent treating agent, in solution or suspenf s ion in a liquid carrier, provision being made 4for circulating the heated mixture of treating agent and liquid carrier in a substantiallyv closed cycle in which vaporized oils discharged from the still are introduced and intimately commingled with the treating mixture to obtain the desired inter- 55 action between the copper oxide and the sulphur compounds in the vvaporized oils, provision also being made for separating'the desulphurized vaporized oils from engagement with the treating mixture and to provide for the subsequent fractionation of said vaporized oils into cuts of con- 5 trolled boiling range.

It is another object of the invention to provide for the desired intimacy of contact of the vapors with the liquid treating mixture in a thorough, uniform and effective manner while 1o continuously maintaining established circulation of the treating mixture and passage of the oil vapors therethrough, so that there will be no accumulation of obstructing solids in the restricted passages of the system which would tend 15 to obstruct fluid flow through the system or materially interfere with its sustained and continuous operation.

It is a further object of the invention to provide the system with means for continuously in- 20 troducing added quantities of fresh treating material into the cycle of treating agent circulation and a proportionate withdrawal of spent treat' ingmaterial from said cycle whereby to obtain uniformity in the desulphurizng of the oils continuously charged to the system.

It is a still further object ofthe invention to provide for the regenerative treatment of the spent treating agent withdrawn from` the system so that the said treating agent may at slight expense be returned to the system for reuse therein.

The invention will be more fully understood from the following description, read in connec- 35 tion with the accompanying drawing, in which:

Fig. i is a diagrammatic view of apparatus suitable for practicing the present invention;

Fig. 2 is a detail sectional view disclosing the contact zones for bringing the vaporized oils into 40 contact with the treating mixture.

Referring to the drawing, crude oil to be treated is withdrawn from a tank l and forced by means of a pump 2 through a pipe line 3. During its passage through the pipe line, the oil enters a heat exchanger l where it is brought into indirect heat exchanging relationship with heated residual oils being withdrawn from the system in order that the crude may be preheated, and the heat economy of the system maintained, prior to the passage of the crude through the heating coils 5 of a tube still 6. The tube still may be of any standard design and theA internal temperatures thereof obtained through the use of suitable. burners 1. The pipe line 3 .communicates with v55 coil 6 adjacent `to thefurnace gas' outlet flue 3. of the still sc -that the temperature'of the oil may be gradually raised during its passage in the form of anV elongated stream of restricted cross.

sectional area through the still. 'Ihe 'temperature imparted tothe oil during its travel through the coils l is sufficient to effect the vaporizatlon of all fractions of such oils which are capable of being vaporized without appreciable molecular decomposition and in this respect theoils and vapors discharged from the still'may possess a temperature of the order. of 600' to 750 F. At

' such a temperature, the naphtha. kerosene and gas oil fractions of the crude will be vaporized, leaving as a liquid only the fuel oil fraction.

To separate and. treat these fractions, the

heated oils and oil vapors discharged from the tube still are passed directlyto a fractionating temperature controls and the like or, if desired,

two fractionating columns maybe employed in lieu of the single-column. whereby to provide the separate chambers Il and Il.

'I'he heated oils and vapors released from the tube still enter the lower chamber II intermediately -of its height through the pipe line I3, and the unvaporized oils gravitate to the base of the chamber II, where they may be additionally heated by the use of a steam coil I4 located in the bottom of the chamber II, to insure the removal of all.. lower boiling and vaporimble constituents from the fuel oil. Connected with the bottom of the chamber II is a draw-olf line il in which is provided a pump I6, by means of which the heated fuel oil is forced through the heat exchanger 4 and then discharged from the system after delivering atleast a part of its heat to the incoming crude oil.

The vaporized oils, ranging from light naphtha to gas oil, after being subjected to fractionation in the chamber II- are released from the upper region of said chamber through a pipe connection I1, and these vapor-ized oils are then transmitted to the lower portion of a treating chamber or tower I8. I'he pipe connection I1 is provided with a vertical section formed to constitute an orifice mixer consisting of a plurality of vertically spaced plates I 9 having restricted ports or orinces formed therein. Entering this orifice mixer is a pipe line 2li, leading from a bank of coils 2I disposed in the furnace gas outlet 22 of the tube still 6. Adapted to be circulated through the coils 2I is a treating mixture'composed of a slurry formed from a relatively heavy oil and copper oxide, and this mixture is heated suiiiciently, during its passage through the coil 2I, so that when said mixture is brought into intimate contact with the oil vapors passing concurrently through the pipe connection I1 and the orice mixer, there will be no material drop in temperature on the part ofv said vapors or condensing of desired low boiling constituents.

'I'he pipe connection I1, beyond the orince mixer, enters the tower or chamber I3 and has its outlet end provided with a drum-shaped head 23, disposed in the conical bottom of the tower Il, the head 23 being formed with horizontal ports, whereby to distribute the mixture of treating agent, oils and vapors as eifectively as possible throughoutthe body of oil or liquid 24 maintained .in the bottom of saidtower. 'Ihe level of this at different vertical heights in the sides of the tower. 'l'he oil vapors bubble-up through the body of carrier cil and copper oxide maintained in the tower so that the desired intimacy of con` tact of the oil vapors with the copper oxide is secured. 'Ihe copper oxide combines with the sulphur compounds present in the oils undergoing treatment to form copper sulphides.

The copper oxide slurry is continuouslywithdrawn from the bottom of the chamber I6 byway of a line 26 through the operation of a hot oil pump 21 and is returned by that pump through a line 23 to the inlet side of the heating coil 2i. The hot oil circulating rate is maintained constant by means of a rate-flow controller 23, arranged in the line 28 and which functions to govern the steam valve 30 regulating the admissons of economy is preferably arranged in the outlet'iiue 22 of the housing of the still 6, and from this heater to the orifice mixer I9 in the vapor line I1. 'I'he circulation rate in a commercial refinery is about thirty barrels per hour. Fresh copper oxide is introduced into the system at the rate of about one and one-half pounds to each barrel of vaporized oil passed through the slurry. The fresh oxide is thoroughly mixed with a heavy oil (although other liquid carriers may be used) and kept in suspension by agitation into relatively small open topped tanks 3 I, which tanks are provided with agitators 32. A circulating pump 33 takes suction from the mixing tank which is ready for use and maintains a pressure against the suction side of a small proportioning pump 34 which is attached to the hot oil circulating pump 21. This proportioning pump introduces fresh slurry at a uniform rate, although this rate may be varied from time to time to secure the proper amount of copper oxide necessary for treating. The outlet side of the pump 34 is connected with a pipe line 35 which line 26, andvthevbottoms of the tanks leads to the 3| are prol In orderto maintain a constant4 level of the treating .slurry in the tower I8, a second proportioning pump 31 is attached to the hot oil pump 21 and functions to remove a. quantity of used slurry at a uniform rate which is directly proportionate lto the rate at which fresh slurry is being added by the operation of the 'pump 34. Thus the suction side of the pump 31 is connected by means of a line 38 with the pipe line 26. and

Ythe outlet side of the pump 31 communicates witha pipe line 33 which leads to a reservoir 40 for the spent slurry. From the reservoir 40, the spent slurry is pumped as at 4I through a. filter press 42 in order to separate the oxide from the oil or other liquid carrier. The filtrate from this press is transferred by way of a line 43 to a tank 44 and may then be pumped as at 45 back to the tanks or mixing release 3I. 'Ihe oxide removed from this vfiltrate is then passed through a revolving type furnace 46 similar to those used in burning clay in order to convert the'copper-gj;v

lil)

Regeneration of copper'sulphide to with medium hlgn temperature:

zcusslaoi-z'cuo-l-zsoa Th following reaction takesplaoelf -perature gs too high.

copper oxide slurry, thereis little if any drop in temperature of the oil vapors contacted with the slurry, so that no additional. reheating of the oils or vapors to fractionating temperatures is necessary following the copper oxide contact.

The fractionating tower I8 may be of any suitable formation but in the present instance, it

is shown as having the upper portion thereof provided with a vapor line 48 through which the naphtha A crude is discharged. The line 48 is provided with a condenser 49 arranged ahead of a separator 58, from which may be separately withdrawn fixed gas, water, a reflux oil and end point A naptha. The reflux oil withdrawn from the separator 58 may be returned -to the upper lportion of the tower I8 for further fractionation and temperature regulation, the returning of the reflux taking place through a pipe line 5I, provided with a pump 52. Water. withdrawn from the separator is released through an outlet connection 53 in the base of the separator, while the fixed gas is withdrawn from an overhead line 54 communicating withthe upper portion of the separator. The end point A naphtha passes from the separator through a line 55 toan aftercooler 58 and thence to a receiving tank 51.

The next cut of higher boiling range may be referred to as the naphtha B crude. This crude or fraction is withdrawn in a substantially liquid state from the upper portion of Lthe tower I8 through any one of a plurality of lines 58 and conducted to the upper chamber 59 of a stripping column 88. The bottom of the chamber 59 may be provided with a steam coilBI to release entrained lower boiling compounds. Liquid oil, constituting the naphtha B crude, is withdrawn from the bottom of the chamber 59 and transferred by means of a. pipe line 52 to a cooler 83 andvthence to a storage tank 84.v Below the chamber 59, the stripping column is provided with an intermediate chamber 85 from which may be withdrawn the so-called naphtha C. Below the pipe lines 58, the fractionating tower I8 -is provided with a multiplicity of corresponding draw-oiI lines 68 by means of which liquid oils of slightly higher bollingrange than the oils passing through the connections 58, are

` .withdrawn from the fractionating tower and are delivered to the chamber 85. This chamber may also be provided with a steam coil 61 in the base thereof to liberate low boiling fractions contained in the oils delivered to the chamber 85. The unvaporized oils which collect in the base of the chamber 85 are discharged through a pipe line 58, containing a cooler 89 and delivered to a nitide/v receiving tank) 1o. vapors released. ln the chamber 85 vmay be returned to the fractlonating column-through a pipe line 1I.

The .kerosene crude is withdrawn from the fractionating towerthrough pipe lines 12 andl vumn 88. This chamber is likewise equipped with a steam 'coil or its equivalent 14 to additionally heat the'liquid oils delivered to the chamber 13 lio-releasel their more volatile compounds, such volatile compounds being then transferred by means of the vapor line 15 back to the fractionating tower. Liquid oils which collect .in the base of the chamber 13 are removed by way of a line 15 provided with a cooler 11 and are delivered to a vstorage. tank 18.

The gas oil fraction may be withdrawn from the base ofthe chamber I8 ofthe fractionating tower and also oil may be withdrawn from the upper portion of the chamber II of said tower by way of a plurality,of branched pipe connections 19. 'Ihese connections lead to the linter mediate portion of. a second oil stripping column 88. In thiscolumn, the oils or vapors delivered thereto are fractionated and, if desired, additionally heated by means of the steam coil 8I located in the base thereof. boiling oils are released from the upper portion of the column 88 and are returned to the tower section I8 by way of the line 15, while the higher boiling oils, which collect in the bottom of the tower 88, are passed by means of a line 82 through a cooler 83 to a gas oil tank 84. vIt will be notedl that the connections 19 are so arranged that oils or vapors can be taken of! either above or below the bulkhead I2 of the tower 9, so that such oils may be treated or untreated with copper oxide as desired. All of the material which passes through the treating tower I8 isvrecovered in a rened state and requires no further chemical treatment. If desired, lime may be introduced into the crude oil flowing through the pipe line 3. The lime may be contained in va tank 85 and pumped as at 88 into the crude oil line 8.

As shown in Fig. 1, reilux oil -in the bottom of the tower section I8 may be withdrawn through a pipe line 81 and delivered to a reservoir 88. This reservoir is connected with thesuction side of a pump 89 and a pipe line 98 leads from the discharge side of said pump to the upper portion of the section II of the fractionating tower 9. 'I'he operation of the pump 89 may be governed by a liquid level controller 9I, which functions upon the attainment of a certain liquid level in the reservoir to start r stop the operation of the pump 89 through the regulation of the steam admission line of the pump,

I'I'he present description should be construed as covering the removal and conversion of sulphur compounds present not only in crude petroleum but other hydrocarbon oils by means of metallic oxides or salts, while copper oxide has been .described as being the preferred reagent to employ in this capacity, and it will be understood that other reagents orcatalysts of a substantially equivalent character may be used. As stated, the process is applicable to hydrocarbon oils other than petroleum and its derivatives. Preferably, the reagent used should be substantially free from moisture and in a fine state of subdivision. In accordance with kthe invention, such an agent, which is capable of combining with sulphur compounds, contained in the oils under treatment. is preferably suspended or dissolved in the hydrocarbon oil or other liquid car- Vapors of lower rier. The invention then comprises heating the mixture of liquid and treating reagent to av suittaining erude or other oils may besimultaneously l fractionally distillecl and desulphurized. This v treatment is accomplished expeditiously, using novel fractionating equipment and accompanied by low operating and treating costs. It will be understood, however, that the particular dlscl'osure of the invention as above given is merely illustrative and applicable to but one of the preferred forms of the present invention and that the latter is subject to considerable variation and modification lwithout departing from the features and scope of the invention as such are defined in the following claims.

What is claimed is:

`1. The method of desulphurizing crude oils, which consists in continuously passing such oils through a tube still maintained at temperatures s'ufiiciently high to substantially vaporize all fractions of such oils which are capable of being vaporized without appreciable molecular decomposition, removing the heated oils and vapors from the tube still and fractionating the same to separate the vaporized oils from the heavier unvaporized oils, passing the vtporized fraction through a confined treating zone and bringing the same in said zone into intimate contact with circulating bodies of copper oxide dissolved or suspended in high boiling liquid oil, whereby to enable said copper oxide to combine'with the undesired sulphur compounds present in the oil vapors to remove such compounds through their combination with the copper oxide, fractionating and condensing the desulphurized oil vapors following their release from the upper portion of the treating zone, collecting unvaporized liquid oil and treating agent in the bottom of said treating zone, heating the mixture of the treating agent and unvaporized oil, returning said heated mixture to the treating zone for reuse therein,l withdrawing spent treating materials from' the* system, and supplying fresh treatingmaterial to the system in amounts proportionate to the withdrawal of the spent material.

y2. The method of refining and fractionating hydrocarbon oils which comprises continuously vaporizing'the oil, contacting the vapors with a desulphurizing agent suspended in high boiling liquid oil heated to substantially the. temperature of the vapors, passing the treated vapors into a fractionating zone, withdrawing a plurality of liquid fractions from said fractionating zone, continuously withdrawing a portion of the 'spentdesulphurlzing agent suspended in oil from the system, separating the oil from the spent reagent, mixing the separated oil with active reagentand returning the mixture to the system for contact with vapors, regenerating the spent reagent and again suspending the regenerated reagent in oil and recirculating the suspended reagent to the system for treatment of further quantities of vapors. A

3. Method according to claim 2 in, which the reagent is copper oxide. y q.

4. I'he method of treating oil which comprises heating the oil to vaporizing temperature, vaporizing the lighter fractions thereof, suspending a desul'phurizing agent in a high boiling oil, heating the suspension to a 'temperature suiilciently high toprevent substantial condensation of said vapors but insumcient to cause substantial vaporization of the high boiling oil, contacting said vapors Iwith said suspension, subsequently fractionating the vapors into a plurality of oils oi' different boiling ranges, continuously withdrawing a portion lof the spent'treating reagent in suspension from the system, continuously addingl active treating reagent in suspension to the system. automatically proportioning the amount of active reagent added to the amount of spent agent withdrawn, separating the oil from the spent reagent, mixing the separated oil with active treating reagent and recircuiating it back to the system, regenerating the spent treating agent, again suspendingthe regenerated reagent in high boiling oil and rrecirculating the suspension back to the system.

5. Method according to claim treating reagent is lcopper oxide.

6. The method of treating oil which comprises heating oil in a restricted stream to a temperature'sumcient to vaporize the lighter fractions without cracking. passing the heated oil into a vaporizing chamber withdrawing vapors and passing the -withdrawn vapors through a treating zone, continuously suspending a desulphurizing 4 in which the reagent in av high boiling point oil, heating the suspension in a restricted stream to a temperature approximately the temperature of said vav pors, contactingthe vapors with the suspension in the treating zone, fractionating the treated vapors to obtain a plurality of fractions, .continuously withdrawing a portion of the spent reagent in suspension from the system, continuously adding active reagent in suspension to the system, automatically proportioning the amount o f active reagent added to. thejamount of spent reagent withdrawn, separating the loil from the 'spent reagent, `suspending 'active reagent in thev separated oil and recirculating the. latterl suspension to thesystem, regenerating the spent reagent and suspending the regenerated reagent in high boiling oil andf'recirculating the regenerated reagent to thesystem.

'1. The method of treating oil which comprises heating oilin a restricted stream to a temperaturesufiicient to vapo the lighter fractions without cracking. passing the heated oil into a vaporizing 4chamber -withdrawing vapors and passing the withdrawn' vapors through a treat- 'to' the system, regenerating the spent reagent and suspending the regenerated reagent in high reagent ma nigh boiling point ou, heating' boiling oil and recirculating the regenerated reagent to the system.

8. The method of reilning hydrocarbon oil which comprises continuously passing oil in a restrictedstream through a furnace wherein the oil is heated to vaporizing temperature, passing the heated oil into a vaporizing chamber wherein the lighter fractions are vaporized, passing the vapors through a body of heavy oil heated to a temperature sufficient to prevent substantial condensation of vapors, said body of oil having suspended therein a desulphurizing agent, fractionating the vapors after contact with said desulphurizing agent to recover gasoline and heavier fractions, continuously withdrawing said heavy oil and spent reagent from said body, separating the oil from the spent reagent, mixing fresh reagent with said separated oil, heating said oil and fresh reagent by v means of waste gases from said furnace to a temperature sumciently high to prevent substantial condensation ot said vapors, and contacting said vapors with the heated oil and fresh reagent.

9. Method according to claim 8 in which the amount of fresh reagent added is automatically proportioned to the amount of spent reagentA withdrawn.

CLYDE L. SMITH. WELDON G. ANNABLE. 

